Sealing putty



SEALING PUTTY Alfred P. Knapp, Jackson Heights, N. L, assignor to Knapp Mills Incorporated, Long Island (City, N. Y., a corporation of New York No Drawing. Application April 17 1953 Serial No. 349,565

7 Claims. (Cl. 106-287) This invention relates to putty-like compositions and particularly to the combination of a metallic powder with a suitable vehicle to form a plastic mixture to act as a sealing putty for cracks, crevices and the like.

The object of the invention is to provide a metal-carrying putty concentrating the metallic content to high density to serve as an effective barrier and seal against injurious radiations.

In the manufacture of equipment and buildings for atomic energy work, for instance, it is vitally important to avoid leakage of the resultant radiation. In spite of the care exercised and the expense involved, cracks and crevices are unavoidable and sometimes develop in use.

The metallic putty of my invention supplies an inexpensive, convenient and reliable seal for these openings, simplifying the original structure and avoiding the necessity of costly time-consuming repair where leaks develop in use.

In the formation of the putty a metallic powder of pro tective ray-absorbing metal, such as lead, is mixed with a relatively slight amount of an oil or grease, acting to coat the individual particles. For example, 15% of Texas Company Crater grease, a semi-fluid lubricant, is mixed with 85% of lead powder by weight, the powder preferably being minus 200 mesh to give a thorough thin filming of the powder particles.

The resulting lead-vehicle mixture would normally have a density much below that of the metal and not sufiicient to satisfactorily prevent the escape of harmful radiation; and I have found that a greatly improved product may be obtained by increased density providing a correspondingly more effective and reliable barrier to the rays.

The desired increase in density is attained by working of the mixture to agglomerate the lead powder particles forcing them to coalesce together and compacting the mixture and presenting a greatly increased ray absorption for a given thickness of the putty barrier. This increase is critical and renders the putty usable in situations where it would otherwise fail.

The relatively greater increase in absorption over the mere gain in total quantity of interposed metal may be due to the greater effectiveness of the coalesced particles in blocking the paths of the rays. Whatever the explanation may be, there is an unexpected improvement in the concentrated structure rendering it far more efiicient in absorption of the injurious rays.

For example, a normal lead putty mixture of the above ingredients having a density of 6.5, after running through an extrusion under high pressure of five hundred pounds per square inch, has its density increased to over 9 and the resulting putty on microscopic examination shows its lead particles in agglomerates of various groupings in which many of the lead particles are in metal to metal contact. Under the pressure applied the grease films on the particle surfaces have been squeezed to extreme thinness and even ruptured either forming a film bond between the adjacent particles or establishing a bond of metal to metal.

assai Patented May a, 195

Other agglomerating procedures such as beating, grinding, hammering and the like may be employed depending on the materials and quantities involved. The important object is to bring the density of the putty as high as possible While still maintaining its pliancy so that it may be pressure-shaped into the cracks and crevices to be filled. The number of particles involve-d in the agglornerates will vary widely and the individual agglomerates themselves are intermediately malleable in that, while firmer than the particle-vehicle mixture, they are more plastic than the solid lead.

Other examples of typical mixtures operating in the same way when mixed and coalesced are 15% Quaker State Viscous-Lube, a pressure gun grease with lead powder and 10% Dow Corning Fluid XF-200, a silicone lubricant, with lead powder, both by weight. Any grease or oil acting to film the metal particles or agglomerates may be employed and the choice of the vehicle will depend on the locality and conditions of use, the crevices to be filled, the temperatures involved, etc.

Instead of lead the powders of other metals such as tungsten may be used, or mixtures thereof may be resorted to where, for instance, the softer acts as a bonding between the others.

In the formation of the putty composition the precise proportions between the metal powder and the binder material are not critical, the objective being to employ as much powder as is practicaL. The oil or grease used should be only sufficient to give a putty-like mass of proper plasticity and a structure which will hold together and can be applied as putty is used to fill cracks, crevices, seams, etc.

The high density is the important criterion, reflecting as it does the necessary agglomeration of the great mass of the metal particles into aggregates in which the particles are closely bound together. The binding forces between the particle surfaces will be thin molecular layers of the oil or grease material and also, preferably in larger part, the cohesion of the metal to metal contact of the metal surfaces as they are forced together by the compressing action of the extrusion, beating, hammering or the like.

The resulting structure presents a cooperative barrier action between the thus aggregated metal particles, greatly augmenting the efliciency of the absorption and simplifying the application of the putty and reducing the expense involved.

The extruded formations may dispense with the binder and the degree of compression will be controlled by the temperature and the intensity of the pressures applied, the metallic surface skin being developed as a containing envelope. Particularly with powders of zinc, lead, tin and cadmium such extrusion may be carried on at room temperatures. With other less soft metals it is desirable to raise the temperature, for instance, to about the recrystallization level such as 150 C. for aluminum and magnesium or 200 C. for copper, silver and gold. In general the extrusion of any metal at about its recrystallization temperature will give the interior con1- pacting of the powder particles to about 70% to of the density of the metal of the powder, and simultaneously the extrusion will develop the substantially continuous metallic surface layer. The result is a bendable rod of sufficient plasticity to be readily pressed and molded into desired shape.

powders may be a mixture of different metals.

In the extruded formation of the powdery material the metal particles tend to accumulate and concentrate at the surface of the rod-like extruding mass developing a metallic surface skin by the welding together of the particles under the pressures applied and the resulting attrition between the material and the containing walls of the casing. A metal tube formation is thus generated '2 M4 holding the compacted material within it and rendering the putty convenient and easy to handle and apply as plastic strips readily bent and compressed into tight and closely fitting engagement with the crevices and openings to be sealed.

The cross-sectional shape of the extruded strips may be of any desired configuration, circular, triangular, rectangular or more intricate designs adapted for most advantageous positioning and inter-fitting with the surfaces of the parts of the apparatus to which it is applied, or r of metal alloys. A soft metal powder such as lead may be mixed with particles of a harder metal, for instance tungsten, to serve as a binder for the latter to correspondingly reduce the temperature and pressure required for the compacting procedures, and the invention is not limparticles and with a relatively small proportion of a soft coating and binding material selected from the group consisting of oils and greases sufficient in amount to film the powder particles, said metal particles being compacted and agglomerated together and coalesced and joined into aggregates of various groupings with metal-tometal contacts between portions of the surfaces of the said particles and by thin intermediate films of said soft material so that the density of the composition is 70% to 95% of the density of the metal of the particles and there is a coalescence of the said metal-tometal contacted particles forming a pliant mass adapted to be pressure shaped into close fitting engagement with said cracks, crevices and the like and adapted to provide a continuous barrier seal against radiation blocked by the metal of said particles of said composition.

2. A putty-like sealing composition as set forth in claim 1 in which the metal powder particles are of the group consisting of lead and tungsten.

3. A putty-like sealing composition as set forth in claim 1 in which the metal powder particles are a mixture of different metals.

4. A putty-like sealing composition as set forth in claim 1 in which the metal powder particles are of the group consisting of lead, tungsten, zinc, tin, cadmium, aluminum, magnesium, silver and gold.

5. A putty-like sealing composition as set forth in claim 1 in which the soft metal powder particles are of lead and the density of the composition is at least 9.5.

6. A putty-like sealing composition as set forth in claim 1 in which the composition consists of a core of the compacted metal particles encased within a surface layer of further compacted particles forming a continuous metallie surface layer for the core.

7. The method of augmenting the ray absorbing effect of a composition of metal powder particles and a relatively small proportion of a lubricant of the group consisting of oils and greases suflicien't to film the powder particles comprising subjecting the composition to pressure of the order of hundreds of pounds per square inch at a temperature at least equal to the highest recrystallization temperature of the metal involved and working the same to develop relative movement between the particles under conditions increasing the density of the composition and forcing the metal particles into agglomerates in which many of the metal particles are in metal-to-metal contact forming a pliant mass having a density substantially to of the density of the metal of the particles and adapted to be pressure-shaped into close fitting engagement with cracks, crevices and the like to be filled and having a greatly increased ray absorption in comparison with the absorption of the composition before said agglomeration of the metal particles.

References Cited in the file of this patent UNITED STATES PATENTS 137,621 Pedderet a1. 'Apr. 8, 1873 1,395,413 Hoffman et'al. Nov. 1, 1921 1,703,634 Podszus Feb. 26, 1929 1,889,842 Parr Dec. 6, 1932' 2,185,194 Harris Jan. 2, 1940 2,263,603 Ziehl Nov. 25, 1941 2,280,135 Ward Apr. 21, 1942 2,369,502 Walker Feb. 13, 1945 2,386,544 Crowley Oct. 9, 1945 2,570,856 Pratt et a1. Oct. 9, 1951 2,618,569 Louton' Nov. 18, 1952 FOREIGN PATENTS 645,030 Great Britain Oct. 25, 1950 OTHER REFERENCES Rudolph C. Buchan, Abstract Ser. No. 165,377, Thread Lubricant, published September 23, 1952. 

1. A PUTTY-LIKE SEALING COMPOSITION HAVING A PLIANCY ADAPTING IT TO BE PRESSURE SHAPED TO FILL CRACKS, CREVICES AND THE LIKE EMITTING INJURIOUS RADIATION, CONSISTING OF A MIXTURE OF A RELATIVELY LARGE PROPORTION OF FINE PROTECTIVE RAY-ABSORBING METAL POWDER PARTICLES INCLUDING SOFT METAL PARTICLES AND WITH A RELATIVELY SMALL PROPORTION OF A SOFT COATING AND BINDING MATERIAL SELECTED FROM THE GROUP CONSISTING OF OILS AND GREASES SUFFICIENT IN AMOUNT TO FILM THE POWDER PARTICLES, SAID METAL PARTICLES BEING COMPACTED AND AGGLOMERATED TOETHER AND COALESCED AND JOINED INTO AGGREGATES OF VARIOUS GROUPINGS WITH METAL-TOMETAL CONTACTS BETWEEN PORTIONS OF THE SURFACES OF THE SAID PARTICLES AND BY THIN INTERMEDIATE FILMS OF SAID SOFT MATERIAL SO THAT THE DENSITY OF THE COMPOSITION IS 70% TO 95% OF THE DENSITY OF THE METAL OF THE PARTICLES AND THERE IS A COALESCENCE OF THE SAID METAL-TO-METAL CONTACTED PARTICLES FORMING A PLIANT MASS ADAPTED TO BE PRESSURE SHAPED INTO CLOSE FITTING ENGAGEMENT WITH SAID CRACKS, CREVICES AND THE LIKE AND ADAPTED TO PROVIDE A CONTINUOUS BARRIER SEAL AGAINST RADIATION BLOCKED BY THE METAL OF SAID PARTICLES OF SAID COMPOSITION. 